CN117044298A - Enhancement of SDT scheme based on multiple RACH - Google Patents

Abstract

A user equipment (300) is described for sending a message to a node (301) during an ongoing communication session, the message comprising a field comprising an indirect indication of the number of remaining data packets of the ongoing communication session to be sent by the user equipment.

Description

Enhancement of SDT scheme based on multiple RACH

Technical Field

The invention relates to a small data transmission (small data transmission, SDT) scheme based on a multiple random access channel (random access channel, RACH).

Background

3GPP release 17 specifies Small Data Transfer (SDT) in radio resource control (radio resource control, RRC) INACTIVE mode.

Existing approaches are more focused on supporting single shot (one data packet) transmissions during small data transmissions. However, to support multiple SDT, many factors need to be considered because multiple process designs may be more complex and additional information exchange may be required between a User Equipment (UE) and the network in order to efficiently support multiple SDT processes.

Qcom proposes in R2-2101223 to utilize UE assistance/traffic pattern information, much like a Configuration (CG) request message in long term evolution (long term evolution, LTE), which can be the basis of any improvement.

The assistance information (or small data request message) may be a Radio Resource Control (RRC) message, and may also include new RRC parameters or MAC Control Elements (CEs) in existing RRC messages. The auxiliary information may be similar to CG request messages for further or subsequent small data transmissions. The UE assistance information message should be able to provide information such as the amount of data in the buffer and/or the future small data traffic profile (i.e., one or more).

The following may be considered in the UE assistance information. First, the buffer status information is considered to indicate the amount of data that may already be in the UE buffer. Second, consider a small data traffic pattern to indicate the type of small data traffic (single or multiple traffic). The traffic pattern may also optionally include periodicity of traffic arrival and possible data volume per traffic occasion in case of multiple traffic.

Fig. 1A and 1B illustrate communication flows between a User Equipment (UE) 100 and a gndeb (gNB) 101. The use of CG allocation in RRC release messages for subsequent data transmission of RACH based STD procedures is shown according to known methods.

In fig. 1A, at 102, in rrc_inactive (rrc_inactive) mode, an RRC resume request, a small data request message, and segmented UL small data are sent from UE 100 to gNB 101. At 103, RRC release (RRCRelease) (+cg configuration) data is sent from the gNB 101 to the UE 100 over MSGB and Downlink (DL) data. At 104, subsequent Uplink (UL) data is sent from UE 100 to gNB 101 on CG resources.

In fig. 1B, at 105, in rrc_inactive mode, a random access preamble is sent from UE 101 to gNB 101 in MSG 1. At 106, a random access response is sent from the gNB 101 to the UE 100 in the MSG 2. At 107, an RRC resume request, a small data request message, and segmented user data are sent from UE 100 to gNB 101 through MSG 3. At 108, RRCRelease (+cg configuration) is sent from the gNB 101 to the UE 100 over MSG 4. At 109, subsequent UL data is sent from UE 100 to gNB 101 on CG resources.

However, there is a problem in transmitting the RRC release message in MSGB or MSG 4. If the RRC release message is transmitted first and then the subsequent data is transmitted, the time at which the SDT procedure ends or the time at which the SDT procedure is considered to be completed is not clear. Furthermore, it is not clear which keys are used to encrypt subsequent packets. For example, it may not be clear whether to receive the new key in the RRC release message or to use the key used to send the first data packet.

Furthermore, if a new key is used in the current session, it is unclear how to pass the new key to the UE for the next session. After the RRC release message, the network cannot send an RRC resume message to transition the UE to an RRC Connected (rrc_connected) state.

There is a need to develop a multiple RACH based SDT scheme in which a UE can transmit or receive multiple small data packets while remaining in RRC INACTIVE mode.

Disclosure of Invention

According to one aspect, there is provided a user equipment for transmitting a message to a node during an ongoing communication session, the message comprising a field comprising an indirect indication of the number of remaining data packets of the ongoing communication session to be transmitted by the user equipment.

The session may be a small data transfer session. In this case, the node may usefully manage aspects of the session according to the indication.

The node may be a target node. The user equipment may be configured to send the message to the target node when transmitting (transiting) from a source node to the target node during the ongoing communication session. In this case, the target node may utilize the indication to help manage the transmission of the session. The node may be a base station. The node may be a gNodeB (gNB).

The user device may store a mapped data number of the remaining data packets to be sent to the data tokens, the user device being operable to select one of the data tokens as the content of the field. This may be a convenient way of determining the appropriate content. The mapping data may be a look-up table or may be stored algorithmically.

The mapping data may map one of the data tokens to zero remaining data packets to be transmitted. This may indicate that the session is about to end.

The mapping data may map one of the data tokens to a remaining data packet to be transmitted. The mapping data may map one of the data tokens to only one remaining data packet to be transmitted. This may be efficient because sessions with a single packet remaining may occur relatively frequently.

The mapping data may map one or more of the data tokens to a corresponding number of ranges of remaining data packets to be transmitted. This may avoid having too many tokens, thereby reducing the number of bits required to represent each token.

These ranges may include one or more of the following: (i) less than two, (ii) less than five, (iii) two to five, (iv) six to ten, (v) less than ten, and (vi) an undefined non-zero number of packets. Wherein one or more may efficiently interrupt the range of possible values.

The user equipment may be configured to send the message as an uplink Radio Resource Control (RRC) message, the communication session being implemented through a Small Data Transfer (SDT) procedure. This may provide compatibility with existing architectures.

The user equipment may be configured to generate the uplink RRC message as an RRC SDT cell update message that is sent as part of a Small Data Transfer (SDT), random Access Channel (RACH) procedure. This may provide compatibility with existing architectures.

The user equipment may be configured to provide downlink packet data convergence protocol (packet data convergence protocol, PDCP) status report data for the communication session for transmission from the target node to the source node. This may facilitate the transfer of the session.

The user equipment may be configured to continue in an rrc_inactive state and maintain PDCP sequence numbers for the ongoing communication session for data radio bearers and signaling radio bearers. This may facilitate the transfer of the session.

According to a second aspect, there is provided a network device for operating as a target node for a user equipment transmitting from a source node to the target node during an ongoing communication session in a communication network, the target node being for: receiving a message from the user equipment as part of the ongoing communication session, wherein the message comprises a field comprising an indirect indication of the number of remaining data packets of the ongoing communication session to be sent by the user equipment; a data forwarding tunnel is established between the source node and the target node in a manner determined based on the indication of the remaining data packets.

The anchor node of the tunnel may be determined from the indication. This may help manage the tunnel.

Whether the session is continued using dynamic authorization or configuration authorization may be determined from the indication. This may enable efficient persistent management of sessions.

The network device may be configured to determine the manner based on the indication. This may enable the network device to manage future processing of the session based on the number of remaining data packets.

The message (which may be a NAS message) or other message received by the network from the user equipment comprises a location measurement report, the network comprising means for determining whether to relocate or anchor the session in dependence on the location measurement report. This may make the management of the session dependent on the location of the user equipment.

The network device may be configured to: transmitting a downlink message to the user equipment in response to the message from the user equipment, the downlink message including one or more of: (i) configuration grant configuration data of the user equipment, (ii) temporary radio network identifier of the user equipment, (iii) physical uplink control channel (physical uplink control channel, PUCCH) and/or sounding reference signal (sounding reference signal, SR) configuration, (iv) next hop chain count (next hop chaining count, NCC), (v) radio link monitoring (radio link monitoring, RLM) and/or Beam Management (BM) configuration for inactive state. This may provide compatibility with existing architectures.

According to a third aspect, there is provided a user equipment for transmitting an uplink message to a node during an ongoing communication session, the uplink message comprising a field comprising a direct or indirect indication of the number of remaining data packets of the ongoing communication session to be transmitted by the user equipment, the user equipment being for employing a subsequent communication mode of the session in response to data received in a downlink response message of the uplink message.

The node may be a target node and the user equipment may be configured to send the message when transmitted from a source node to the target node during the communication session. This may facilitate the transfer of the session.

The user equipment may respond to the downlink response message including one or more of: (i) configuration grant configuration data of the user equipment, (ii) temporary radio network identifier of the user equipment, (iii) Physical Uplink Control Channel (PUCCH) and/or sounding reference signal configuration, (iv) next hop chain count (NCC), (v) Radio Link Monitoring (RLM) and/or Beam Management (BM) configuration for inactive state, (vi) collision resolution information. This may provide compatibility with existing architectures.

The apparatus may be configured to stop a timer started in response to an RRC resume request message or a function similar message thereof upon receipt of the downlink message. This may eliminate ambiguity when to stop such a timer. The timer may be a T319 timer.

The user equipment may be configured to authenticate the connected network via the downstream message and to continue data transmission in accordance with the message only if the network is authenticated. This may avoid continuing to use the wrong network.

The user equipment may be configured to interrupt monitoring of a control channel in response to the downlink message. This may reduce the consumption of resources. The control channel may be an L1 control channel PDCCH.

The downlink message may include a field for the user equipment to respond to maintaining a small data transfer session. This may cause the network to signal whether to continue such a session.

The user equipment may respond to the downlink message not including the field to terminate the small data transfer session. This may cause the network to interrupt such sessions.

The downlink message may be a downlink RRC message. This may provide compatibility with existing architectures.

The user equipment may be configured to send a power headroom report to a network node in response to a non-zero number of remaining data packets to be sent for the ongoing communication session. This may help the network manage the session.

Drawings

The invention will now be described by way of example with reference to the accompanying drawings. In the drawings:

fig. 1A and 1B schematically illustrate communication flows between a User Equipment (UE) and a gndeb (gNB), illustrating subsequent data transmission using CG allocation in an RRC release message for RACH-based STD procedures.

Fig. 2 shows a flow chart of an example of steps performed by a target node in a communication system.

Fig. 3A and 3B illustrate communication flows between a User Equipment (UE) and a gndeb (gNB) provided by an embodiment of the present invention.

Detailed Description

Embodiments of the present invention may provide a scheme in which a UE device is capable of transmitting or receiving multiple small data packets while remaining in RRC INACTIVE mode, and using the methods described herein, may enhance the multiple SDT process by enhancing UE traffic pattern information.

In embodiments of the present invention, the traffic pattern information sent from the UE device may be enhanced such that it contains an index to a look-up table, which may indicate a range of the number of subsequent data packets to be sent, or contains the exact number of data packets to be sent.

In general, as will be described in more detail below, the UE may be configured to send a message to the node during an ongoing communication session, the message including a field including an indirect indication of the number of remaining data packets to be sent by the user equipment for the ongoing communication session.

Such granularity or accurate information about the number of data packets to be sent may provide the network with complete flexibility to make decisions to continue with Dynamic Grant (DG) or with Configured Grant (CG) for subsequent transmissions in the current SDT session based on traffic pattern information received with MSG a or MSG3 and other factors such as device battery, device mobility, and network load conditions.

Signaling this information may provide complete flexibility for the network to make decisions based on the received traffic pattern information to efficiently allocate resources to conserve UE power, as will be described in more detail below.

For SDT, there may be many cases where the number of occasions/packets to be sent for subsequent data may be known in advance at the UE. The same is true for the case where the SDT is used to send NAS signaling messages containing location measurement reports (possibly configured as periodic reports) to the network.

Examples of such periodic traffic include (R2-2006582) heartbeat/keep-alive traffic from IM/email clients and other applications, traffic from wearable devices (e.g., periodic location information, etc.), industrial wireless sensor networks that send temperature or pressure readings periodically, smart meters that send periodic meter readings, and smart meter networks.

Parameters such as requestenumtimes may not be granular, indicating the number of PUR grant occasions requested in LTE within a PUR configuration request (PUR configuration request) message. There are two possible values for this value: 1 and infinity, both possible values are not valid from the resource allocation point of view of the SDT. Improvements are desirable because SDTs will support a wide variety of use cases.

To enhance traffic pattern information within MSG3, the UE may provide a number of occasions/packets to be transmitted, e.g., by an index to a look-up table (as shown in table 1), or the exact number of packets, as well as the requested TBS and periodicity.

In the example shown in table 1, the index uses only three bits, and enough information can be provided to the network for selecting between DG and CG resource allocations.

TABLE 1

Index	Packet number of subsequent SDT data
		0	0
1	1
		2	≤2
3	≤5
		4	≤10
……	……
		7	Infinite number of cases

Some possible variations for indicating the number of data packets for transmission may include:

(i) In the case where the SDT procedure is started, the remaining number of data packets to be transmitted=the total number of data packets to be transmitted in the SDT session-1 (initial transmission);

(ii) The remaining number of data packets to be sent (in the target cell after cell reselection) =total number of data packets to be sent (data packets already sent/acknowledged in the source cell) in the SDT session;

(iii) Subsequent transmissions (true/false) required;

(iv) Any variation of the ranges shown in table 1.

Other implementations are also possible.

This may also be useful when SRB 2 is used to send NAS signaling messages containing positioning measurement reports that are periodic in nature. In this case, the information may be referred to AS an AS layer or notified from the NAS layer to the AS layer.

This information may also be sent to the last serving gNB node to make decisions to relocate or anchor the SDT session when the SDT session originates in a non-anchor gNB, or when the UE performs a cell reselection and leaves the serving gNB during the SDT session.

Thus, in some implementations, the node to which the message is sent from the UE may be a target node, such as a gNB or other base station. The UE may be configured to send a message to the target node when transmitting from the source node to the target node during an ongoing communication session. In this case, the target node may utilize the indication to help manage the transmission of the session.

The UE may store mapped data numbers of remaining data packets to be sent to the data tokens and may be used to select one of the data tokens as the content of the field. As described above, the mapping data may be a look-up table or may be stored algorithmically. The mapping data may conveniently map one of the data tokens to zero remaining data packets to be transmitted, which may indicate that the session is over.

The mapping data may map one of the data tokens to a remaining data packet to be transmitted. The mapping data may map one of the data tokens to only one remaining data packet to be transmitted. This may be efficient because sessions with a single packet remaining may occur relatively frequently.

The mapping data may map one or more of the data tokens to a corresponding number of ranges of remaining data packets to be transmitted. This may avoid having too many tokens, thereby reducing the number of bits required to represent each token. As shown in table 1 above, in one implementation, the range includes (i) less than two, (ii) less than five, (iii) two to five, (iv) six to ten, (v) less than ten, and (vi) an undefined non-zero number of packets.

To be compatible with existing architectures, the UE may be used to send the message as a UL RRC message. The UE may be configured to generate an uplink RRC message as an RRC SDT cell update message that is sent as part of a Small Data Transfer (SDT), random Access Channel (RACH) procedure.

To facilitate transmission of the session, the UE may be configured to provide downlink Packet Data Convergence Protocol (PDCP) status report data for the communication session for transmission from the target node to the source node. The UE may be configured to continue in the rrc_inactive state and maintain PDCP sequence numbers for the ongoing communication session for the data radio bearer and the signaling radio bearer.

Thus, as described above, the UE may provide multiple opportunities/packets to transmit with an index to a lookup table or the exact number of packets to be transmitted to the network. This may apply to CG and RACH based schemes. Such granularity or accurate information may provide the network with complete flexibility in terms of the number of data packets to be transmitted to decide whether to use DG or CG for subsequent transmission in the current RACH based SDT session.

In some implementations, a target node of a UE may transmit from a source node to the target node during an ongoing communication session. In this case, the target node may be used to perform the steps shown in the method flow chart 200 of fig. 2. In step 201, the method comprises: as part of an ongoing communication session, a message is received from a user device, the message comprising a field comprising an indirect indication of a number of remaining data packets of the ongoing communication session to be transmitted by the user device. In step 202, the method includes establishing a data forwarding tunnel between the source node and the target node in a manner determined based on the indication of the remaining data packets.

Based on the indication, one or more of the following determinations may be made. The anchor node of the tunnel may be determined, which may help manage the tunnel. It can be determined whether the session continues using DG or CG, which can enable efficient, continuous management.

The network device may be configured to determine a manner based on the indication, which may cause the network device to manage future processing of the session based on the number of remaining data packets.

The message (which may be a NAS message) or other message received by the network from the user equipment may comprise a location measurement report, and the network may comprise means for determining whether to relocate or anchor the session in dependence on the location measurement report. This may make the management of the session dependent on the location of the user equipment.

The network device may be configured to: in response to the message from the UE, sending a downlink message to the user equipment, the downlink message including one or more of: (i) configuration grant configuration data of the user equipment, (ii) temporary radio network identifier of the user equipment, (iii) Physical Uplink Control Channel (PUCCH) and/or sounding reference Signal (SR) configuration, (iv) next hop chain count (NCC), (v) Radio Link Monitoring (RLM) and/or Beam Management (BM) configuration for inactive state. This may provide compatibility with existing architectures.

Enhancement of the multiple SDT procedure can also be achieved by introducing a new DL RRC message between the RRC resume request and the RRC release message, which can act as an RRC reconfiguration message and can signal any required configuration during the SDT procedure.

The introduction of such a message may signal or alter any desired configuration during the multiple SDT process. Since the multiple SDT procedure will be longer than the single shot SDT procedure, the introduction of this message may also help solve existing problems associated with the multiple shot SDT procedure, assuming that no DL message is used in addition to the RRC release message that terminates the SDT procedure. The new DL RRC message introduced here (referred to as an RRC SDT restore message) may be sent in response to the RRC restore request.

To illustrate this aspect, fig. 3A shows an exemplary communication flow between a User Equipment (UE) 300 and a gndeb (gNB) 301. The gNodeB may be a base station or other network device.

At the beginning of the communication flow, the UE is in rrc_inactive mode. The SDT procedure then begins, for example, because the UE wants to send data to the GNB.

Message 1 (MSG 1) is sent from the UE to the gNB. This is an SDT indication that the UE wishes to start an SDT session.

Message 2 (MSG 2) is then sent from the gNB to the UE. This is an authorization that allows SDT sessions to continue (development).

Message 3 (MSG 3) is then sent from the UE to the gNB. This is an RRC resume request with uplink data. This provides information to establish the SDT session, such as BSR and enhanced traffic pattern information.

Then, a message 4 is sent from the network device to the UE. This is a message called RRC SDT restore message. The RRC SDT restore message may carry a series of optional information that the UE may use to help establish the session. Some non-limiting examples include contention resolution information, configuration grant configuration information, information about control channels, NCC information and I-RNTI information, and an indication that a device is transmitting a power headroom report (power headroom report, PHR). The UE may later use any of this information when setting up the session.

Depending on the content of the message 4 and optionally also on the configuration of the UE and the network, the session may continue in Dynamic Grant (DG) or Configuration Grant (CG) mode.

These options are listed in fig. 3A. For the case of DG, the session continues by sending DCI messages on the downlink and subsequent uplink data on the uplink, as shown in fig. 3A. For the CG case, the session is continued by sending subsequent uplink data on the uplink.

At the end of the session, the gNB sends an RRC release message. The SDT procedure ends and the UE enters RRC Inactive mode.

Fig. 3B shows an alternative communication flow between a User Equipment (UE) 300 and a gndeb (gNB) 301. The gNodeB may be a base station or other network device.

At the beginning of the communication flow, the UE is in rrc_inactive mode. The SDT procedure then begins, for example, because the UE wants to send data to the gNB.

The UE sends a message a (MSGA) to the gNB. This is an RRC resume request with uplink data. This provides information to establish the SDT session, such as BSR and enhanced traffic pattern information.

Message B is then sent from the network device to the UE. This is a message called RRC SDT restore message. The RRC SDT restore message may carry a series of optional information that the UE may use to help establish the session. Some non-limiting examples include contention resolution information, configuration grant configuration information, information about the control channel, such as NCC information and I-RNTI information. The UE may later use any of this information when setting up the session.

Depending on the content of the message B and optionally also on the configuration of the UE and the network, the session may continue in Dynamic Grant (DG) or Configuration Grant (CG) mode.

These options are listed in fig. 3B. For the case of DG, the session continues by sending DCI messages on the downlink and subsequent uplink data on the uplink, as shown in fig. 2B. For the CG case, the session is continued by sending subsequent uplink data on the uplink.

At the end of the session, the gNB sends an RRC release message. The SDT procedure ends and the UE enters RRC Inactive mode.

The UE may be configured to transmit an uplink message to the node during the ongoing communication session, the uplink message including a field including a direct or indirect indication of a number of remaining data packets of the ongoing communication session to be transmitted by the user equipment, the user equipment being configured to employ a subsequent communication mode of the session in response to data received in a downlink response message of the uplink message.

The node may be a target node and the UE may be configured to send messages when transmitting from the source node to the target node during the communication session, which may facilitate transmission of the session.

The UE may respond to a downlink response message that includes one or more of: (i) configuration grant configuration data of the user equipment, (ii) temporary radio network identifier of the user equipment, (iii) Physical Uplink Control Channel (PUCCH) and/or sounding reference signal configuration, (iv) next hop chain count (NCC), (v) Radio Link Monitoring (RLM) and/or Beam Management (BM) configuration for inactive state, (vi) collision resolution information. This may provide compatibility with existing architectures.

The UE may be configured to stop a timer started in response to the RRC resume request message or a function similar message thereof upon receipt of the downlink message. This may eliminate ambiguity when to stop such a timer. In a preferred embodiment, the timer is a T319 timer.

The UE may be used to authenticate the connected network by a downlink message and only if the network is authenticated, continue data transmission according to the message, which may avoid continuing to use the wrong network.

The UE may be configured to interrupt monitoring of the control channel in response to the downlink message. This may reduce the consumption of resources. The control channel may be an L1 control channel PDCCH.

The downlink message may include a field for the UE to respond to maintaining the small data transfer session, which may cause the network to signal whether to continue such session.

The UE may respond to the downlink message not including the field to terminate the small data transfer session, which may cause the network to interrupt such a session.

To provide compatibility with existing architectures, the downlink message may be a downlink RRC message.

If there is a subsequent uplink transmission of the data packet after the first data packet transmission, the UE may trigger a transmit power headroom report (power headroom report, PHR), (i.e., where the number of subsequent data packets to be transmitted is greater than 0).

Some of the advantages of introducing an RRC SDT restore message are as follows.

The RRC SDT restore message may be used as a response message to the RRC restore request of the multiple SDT procedure. The T319 timer may stop upon receipt of the RRC SDT restore message, and then the SDT procedure may depend to a large extent only on the number of data packets to be sent and the desired periodicity.

The RRC SDT restore message may be used for network authentication from the UE's perspective by receiving the RRC SDT restore message on a dedicated control channel (dedicated control channel, DCCH) before continuing with subsequent data transmissions.

The RRC SDT restore message may be used to carry configurable grantconfig in case the CG is used for subsequent transmissions in this SDT session.

The RRC SDT restore message may provide a reliable way to deliver the contention resolution MAC CE in the new message.

The RRC SDT recovery message may be used to signal the reserved NCC, I-RNTI, for use in case a subsequent RRC recovery request is triggered due to data arrival of a non-SDT DRB.

The RRC SDT restore message may be used for NW configuration INACTIVE SRS for carrier switching between Normal Uplink (NUL) and supplementary uplink (supplementary uplink, SUL) of the SDT. The SRS transmission can only be performed during subsequent transmissions, i.e. only when there are multiple transmissions.

The RRC SDT recovery message may be used as a substitute message for the RRC cell update confirm message if the RRC recovery request is reused for the cell reselection procedure in the target cell. In this message, the new NCC, I-RNTI may be provided in the target cell for subsequent transmission.

In general, the RRC SDT restore message may also reduce the specification impact, as the procedure may define a new DL RRC message that may be used for multiple purposes.

The RRC SDT restore message may be used for a variety of purposes, with advantages including the following.

As described above, this message may help to eliminate ambiguity when to stop the T319 timer. The RRC SDT recovery message may be a response message to the RRC recovery request message of the multiple SDT procedure. T319 may stop upon receipt of the RRC SDT restore message, and then the SDT procedure may depend largely only on the number of data packets to be sent and the desired periodicity, while taking into account the different traffic patterns of the use case.

The message may also enable network authentication of the UE. The RRC SDT restore message may be used for network authentication from the UE's perspective by receiving the RRC SDT restore message on the DCCH before continuing with the subsequent data transmission.

The RRC SDT recover message may also be used to carry the contention resolution (contention resolution, CR) MAC CE.

The RRC SDT restore message may be used to carry various configuration parameters of the UE, such as (I) configured grant configuration, in case the CG is used for subsequent transmissions within this SDT session, (ii) reserved NCC, I-RNTI for use in case a subsequent RRC restore request is triggered due to data arrival of non-SDT DRBs, and (iii) INACTIVE SRS configuration for configuring SDT carrier switching.

The message may also be used as a response message to the RRC resume request during cell reselection. If the RRC recovery request is reused for the cell reselection procedure, the RRC SDT recovery message may be used as a response message to indicate that the cell update procedure was successful and may carry a new NCC, I-RNTI for the UE in the target cell.

Applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features. Such features or combinations can be implemented as a whole in accordance with the present specification, irrespective of whether such features or combinations of features solve any problems disclosed herein, as long as such features or combinations are known to those of ordinary skill in the art; and do not limit the scope of the claims. The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features. In view of the above description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.

Claims (31)

1. A user equipment (300) for sending a message to a node (301) during an ongoing communication session, the message comprising a field comprising an indirect indication of the number of remaining data packets of the ongoing communication session to be sent by the user equipment.

2. The user equipment of claim 1, wherein the session is a small data transfer session.

3. A user equipment according to claim 1 or 2, wherein the node is a target node, the user equipment being arranged to send the message to the target node when transmitting from a source node to the target node during an ongoing communication session.

4. A user device according to any preceding claim, wherein the user device stores a mapped data number of remaining data packets to be sent to a data token, the user device being operable to select one of the data tokens as the content of the field.

5. The user equipment of claim 4, wherein the mapping data maps one of the data tokens to zero remaining data packets to be transmitted.

6. A user equipment according to any preceding claim, wherein the mapping data maps one of the data tokens to one remaining data packet to be transmitted.

7. A user equipment according to any preceding claim, wherein the mapping data maps one of the data tokens to only one remaining data packet to be transmitted.

8. The user equipment of any of claims 4 to 7, wherein the mapping data maps one or more of the data tokens to a respective range of remaining data packets to be transmitted.

9. The user device of claim 8, wherein the range comprises one or more of: (i) less than two, (ii) less than five, (iii) two to five, (iv) six to ten, (v) less than ten, and (vi) an undefined non-zero number of packets.

10. A user equipment according to any of the preceding claims, the user equipment being configured to send the message as an uplink radio resource control, RRC, message, the communication session being effected by a small data transfer, SDT, procedure.

11. The user equipment of claim 10, wherein the user equipment is configured to generate the uplink RRC message as an RRC SDT cell update message that is sent as part of a small data transfer, SDT, random access channel, RACH, procedure.

12. A user equipment according to any preceding claim, wherein the user equipment is adapted to provide downlink packet data convergence protocol, PDCP, status report data for the communication session for transmission from the target node to the source node.

13. A user equipment according to any preceding claim, wherein the user equipment is operable to continue in an rrc_inactive state and maintain PDCP sequence numbers for the ongoing communication session for data radio bearers and signaling radio bearers.

14. A network device (301) for operating as a target node of a user equipment (300), the user equipment (300) transmitting from a source node to the target node during an ongoing communication session in a communication network, the target node being for:

receiving a message from the user equipment as part of the ongoing communication session, wherein the message comprises a field comprising an indirect indication of the number of remaining data packets of the ongoing communication session to be sent by the user equipment;

a data forwarding tunnel is established between the source node and the target node in a manner determined based on the indication of the remaining data packets.

15. The network device of claim 14, wherein an anchor node of the tunnel is determined from the indication.

16. The network device of claim 14 or 15, wherein whether the session is to continue using dynamic authorization or configuration authorization is determined from the indication.

17. The network device of any of claims 14 to 16, wherein the network device is configured to determine the manner in accordance with the indication.

18. A network device as claimed in any of claims 14 to 17, wherein the message or other message received by the network from the user device comprises a location measurement report, the network comprising means for determining whether to relocate or anchor the session in dependence on the location measurement report.

19. The network device of any of claims 14 to 18, the network device to:

transmitting a downlink message to the user equipment in response to the message from the user equipment, the downlink message including one or more of: (i) configuration grant configuration data of the user equipment, (ii) temporary radio network identifier of the user equipment, (iii) physical uplink control channel, PUCCH, and/or sounding reference signal, SR, configuration, (iv) next hop chain count, NCC, (v) radio link monitoring, RLM, and/or beam management, BM, configuration for inactive state.

20. A user equipment (300) for transmitting an uplink message to a node (301) during an ongoing communication session, the uplink message comprising a field comprising a direct or indirect indication of the number of remaining data packets of the ongoing communication session to be transmitted by the user equipment, the user equipment being arranged to employ a subsequent communication mode of the session in response to data received in a downlink response message of the uplink message.

21. The user equipment of claim 20, wherein the node is a target node, the user equipment to send the message when transmitting from a source node to the target node during the communication session.

22. The user equipment of claim 20 or 21, wherein the user equipment is responsive to the downlink response message comprising one or more of: (i) configuration grant configuration data of the user equipment, (ii) temporary radio network identifier of the user equipment, (iii) physical uplink control channel, PUCCH, and/or sounding reference signal configuration, (iv) next hop chain count, NCC, (v) radio link monitoring, RLM, and/or beam management, BM, configuration for inactive state, (vi) collision resolution information.

23. A user equipment according to any of claims 20 to 22, wherein the device is configured to stop a timer started in response to an RRC resume request message or a functional analogue thereof upon receipt of the downlink message.

24. The user equipment of claim 23, wherein the timer is a T319 timer.

25. A user equipment according to any of claims 20 to 24, wherein the user equipment is arranged to authenticate a connected network by means of the downstream message and to continue data transmission in accordance with the message only if the network is authenticated.

26. The user equipment of any of claims 20 to 25, wherein the user equipment is configured to interrupt monitoring of a control channel in response to the downlink message.

27. The user equipment of claim 26, wherein the control channel is an L1 control channel PDCCH.

28. The user equipment of any of claims 20 to 27, wherein the downlink message comprises a field for the user equipment to respond to maintaining a small data transfer session.

29. The user equipment of claim 28, wherein the user equipment is responsive to the downlink message not including the field to terminate a small data transfer session.

30. The user equipment of claim 28 or 29, wherein the downlink message is a downlink RRC message.

31. The user equipment of any of claims 1 to 13 or 20 to 30, the user equipment being configured to send a power headroom report to a network node in response to there being a non-zero number of remaining data packets to be sent for the ongoing communication session.